It is the purpose of this code, in establishing programs and services which are designed to provide protection, support or care of children, to provide protective services to the fullest extent deemed necessary by the juvenile court, probation department or other public agencies designated by the board of supervisors to perform the duties prescribed by this code to insure that the rights or physical, mental or moral welfare of children are not violated or threatened by their present circumstances or environment. Such essential services may be provided irrespective of whether the child or the family of the child is otherwise known to the responsible local agency.